JP2012039351A - Electromagnetic coupler and information communication device mounted with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic coupler capable of increasing coupling strength and widening coupling range and making a frequency bandwidth to be used a wideband even if the electromagnetic coupler is made thin.SOLUTION: An electromagnetic coupler comprises: an electrically conductive pattern 11 formed on a first plane; a power feeding pattern 13 formed on a second plane parallel to the first plane and connected to a power feeding system 12; a ground pattern 14 formed on the second plane spaced from the feeding pattern 13 and grounded; a first linear conductor 15 formed perpendicularly to the first and second planes and connecting the electrically conductive pattern 11 and the feeding pattern 13; and a plurality of second linear conductors 16 formed perpendicularly to the first and second planes and connecting the electrically conductive pattern 11 and the ground pattern 14. The electrically conductive pattern 11 is formed in a shape of a point symmetry with respect to a connecting point with the first linear conductor 15 and the plurality of second linear conductors 16 are formed at positions of a point symmetry with respect to the first linear conductor 15 in a plan view.

Description

  The present invention relates to an electromagnetic coupler suitable for a wireless communication system for transmitting information between information communication devices arranged at a short distance using an electrostatic field or an induction electric field, and an information communication device equipped with the electromagnetic coupler.

  As a conventional electromagnetic coupler, there is an electromagnetic coupler described in Patent Document 1. This electromagnetic coupler (high frequency coupler) is configured by connecting electrodes on a flat plate, a series inductor, and a parallel inductor through a high frequency signal transmission path. In addition, the electromagnetic coupler is disposed in an information communication device such as a transmitter or a receiver. When the transmitter and receiver are arranged so that the electrodes of the respective electromagnetic couplers face each other, if the distance between the two electrodes is 2λ / 15 or less of the wavelength of the frequency used, the two electrodes are longitudinal waves. Since they are coupled by an electrostatic field component, operate as one capacitor, and operate as a band pass filter as a whole, information can be efficiently transmitted between the two electromagnetic couplers. In addition, when the distance between the two electrodes is 2λ / 15 to 8λ / 15 of the wavelength of the frequency to be used, information can be transmitted using an induced electric field of longitudinal waves.

  On the other hand, when the distance between the electromagnetic couplers is a predetermined distance or more, information cannot be transmitted. For this reason, other radio communication systems are not disturbed by electromagnetic waves generated from the electromagnetic coupler, and a radio communication system using an information communication device including the electromagnetic coupler does not receive interference from other radio communication systems. It has the characteristics. Based on these characteristics, according to a conventional wireless communication system using an electromagnetic coupler, information communication is performed by a UWB (Ultra Wide Band) communication method using a long-wave electrostatic signal or an induced electric field at a short distance and using a broadband signal. Large-capacity data communication can be performed between devices.

  More specifically, in the electromagnetic coupler of Patent Document 1, a through hole formed in a cylindrical dielectric is filled with a conductor, and a conductor pattern serving as an electrode is formed on the upper end surface of the cylindrical dielectric. A cylindrical dielectric is mounted on a printed circuit board on which a conductor pattern serving as a high-frequency transmission path is formed, and the high-frequency transmission path and the electrode are connected via a conductor in the through hole. The conductor in the through hole serves as a substitute for the above-described series inductor, and the high-frequency transmission line and the ground pattern are connected via a parallel inductor. When power is supplied to this electromagnetic coupler, a longitudinal wave of the electric field is generated in the direction parallel to the conductor in the through hole (current flowing through the conductor in the through hole) in the conductor in the through hole. It is configured to transmit information using it.

Japanese Patent No. 4345851 JP 2006-121315 A

Osamu Haneishi, two others, “Small / Plane Antenna”, The Institute of Electronics, Information and Communication Engineers, p. 23

  The electromagnetic coupler is built in, for example, a personal computer (PC), a mobile phone, a digital camera, and the like, and is used to transmit / receive data such as a moving image to / from each other. Since an electromagnetic coupler is built in a small device such as a mobile phone or a digital camera, it is required to be thin.

  However, in the electromagnetic coupler of Patent Document 1, in order to reduce the thickness, it is necessary to shorten the cylindrical dielectric, and the conductor in the through hole is shortened. When the conductor in the through hole is shortened, the electric field generated by the conductor in the through hole is reduced, and the longitudinal wave of the electric field used for information transmission is also reduced, so the electromagnetic coupler on the transmission side and the electromagnetic coupler on the reception side There arises a problem that the bonding strength between the two becomes small.

  In addition, since the coupling strength between the transmission-side electromagnetic coupler and the reception-side electromagnetic coupler decreases, the information increases when the distance between the transmission-side electromagnetic coupler and the reception-side electromagnetic coupler increases. Cannot be transmitted, and the position of the receiving-side electromagnetic coupler is slightly shifted from the transmitting-side electromagnetic coupler, so that information cannot be transmitted and the coupling range becomes narrow.

  Further, in the electromagnetic coupler of Patent Document 1, when the thickness is reduced, the electrode approaches the ground, and the impedance characteristic (impedance characteristic with respect to frequency) becomes steep. On the other hand, the input impedance of the feeding system is constant. There is also a problem that the usable frequency band (that is, the frequency band where the matching condition between the electromagnetic coupler and the power feeding system is good) becomes narrow.

  Further, in the electromagnetic coupler of Patent Document 1, when the distance between the electrodes of the two electromagnetic couplers is 2λ / 15 or less of the wavelength of the frequency used, information is efficiently transmitted by realizing a band pass filter. However, there is a problem that the efficiency of signal transmission is deteriorated when the compatibility with the counterpart electromagnetic coupler is not good.

  Furthermore, for example, when the electromagnetic coupler of Patent Document 1 is mounted inside a device for wireless communication, there is a cover of the device including a dielectric between the electromagnetic couplers, so that the dielectric constant between the electromagnetic couplers is increased. Change. If it does so, the capacitance value between the electrodes of two electromagnetic couplers will change, the frequency characteristic of a band pass filter will change, and there exists a problem that the information transmission characteristic in a desired frequency band deteriorates depending on the case. In this case, even if the electromagnetic coupler is designed based on these changes in the dielectric constant, the dielectric constant between the electromagnetic couplers becomes a different value if the device that performs wireless communication is further different. Similarly, the information transfer characteristic of wireless communication is deteriorated.

  In addition, in the electromagnetic coupler of Patent Document 1, when the distance between the electrodes of the two electromagnetic couplers is 2λ / 15 to 8λ / 15 of the wavelength used, information of the information using the induced electric field component of the longitudinal wave is used. In this case, when the arrangement of the two electromagnetic couplers and the surrounding environment are constant, the information transmission characteristic depends on the matching condition between the electromagnetic coupler and the power feeding system. In other words, when the matching conditions are good, the signal strength from the electromagnetic coupler to the communication module including the power feeding system increases. Conversely, when the matching conditions are poor, the signal strength from the electromagnetic coupler to the communication module including the power feeding system is small. Become.

  Therefore, the electromagnetic coupler of Patent Document 1 realizes a bandpass filter when the distance between the electromagnetic couplers (the distance between the two electrodes) is 2λ / 15 or less of the wavelength of the frequency used, and the electromagnetic coupler The electromagnetic coupler must be designed so that the matching condition is good when the distance between the couplers is 2λ / 15 to 8λ / 15 of the wavelength of the frequency used. Therefore, for example, when the signal strength is insufficient when the distance between the electromagnetic couplers is 2λ / 15 to 8λ / 15 of the wavelength of the used frequency, the distance between the electromagnetic couplers is 2λ / of the wavelength of the used frequency. Redesign is required including the realization of the bandpass filter in the case of 15 or less, and it takes time to design the electromagnetic coupler. Further, when the frequency band to be used is wide, it is necessary to realize a large number of frequencies for which matching conditions are appropriate, and it takes much time for designing.

  Accordingly, an object of the present invention is to provide an electromagnetic coupling capable of solving the above-described problems and increasing the coupling strength, widening the coupling range, and widening the frequency band to be used even when the thickness is reduced. And providing an information communication device equipped with the device.

  Another object of the present invention is to provide an electromagnetic coupler in which the information transfer characteristic is hardly dependent on the dielectric constant between the electromagnetic couplers, and an information communication device equipped with the same while maintaining the same information transfer characteristic as that of the prior art. It is in.

  Furthermore, an object of the present invention is to provide an electromagnetic coupler capable of easily performing matching adjustment with a power feeding system and adjustment of a frequency band while maintaining information transmission characteristics equivalent to those of a conventional one, and an information communication device equipped with the same Is to provide.

  The present invention was devised to achieve the above object, and is formed on a conductive pattern formed on a first plane and a second plane parallel to the first plane, and connected to a power feeding system. A power supply pattern, a ground pattern formed on the second plane and spaced from the power supply pattern, and grounded, and formed perpendicular to the first plane and the second plane, and the conductive pattern. A first linear conductor connecting the power supply pattern and a plurality of second conductors formed perpendicular to the first plane and the second plane and connecting the conductive pattern and the ground pattern. The conductive pattern is formed in a shape that is point-symmetric with respect to a connection point with the first linear conductor, and the plurality of second linear conductors are planarly viewed. The electromagnetic formed at a position that is point-symmetric with respect to the first linear conductor It is a case unit.

  The first plane is one surface of the printed circuit board, the second plane is the other surface of the printed circuit board, and the first linear conductor and the second linear conductor are: It may be a conductor formed inside a through hole formed in the printed board.

  The printed circuit board has a relative dielectric constant of 4.0 to 5.0, and a thickness of 6λ / 1000 to 45λ / 1000, where λ is a wavelength of a frequency to be used. The distance from the connection point of one linear conductor to the connection point of the conductive pattern and the second linear conductor is 75λ / 1000 to 225λ / 1000, and the conductive pattern is a length of one side. May be formed in a square shape of 225λ / 1000 to 450λ / 1000.

  The ground pattern may be formed so as to surround the power supply pattern, and the conductive pattern may be formed at a position facing the power supply pattern and the ground pattern.

  The present invention is also an information communication device equipped with an electromagnetic coupler and transmitting information using at least one of an electrostatic field and an induced electric field, wherein the electromagnetic coupler is a conductive material formed on a first plane. A pattern, a power supply pattern formed on a second plane parallel to the first plane, connected to a power supply system, and a ground pattern formed on the second plane spaced apart from the power supply pattern and grounded A first linear conductor formed perpendicular to the first plane and the second plane and connecting the conductive pattern and the power feeding pattern; the first plane; and the second plane A plurality of second linear conductors formed perpendicular to a plane and connecting the conductive pattern and the ground pattern, wherein the conductive pattern is at a connection point with the first linear conductor. A plurality of second lines formed in a point-symmetric shape with respect to the plurality of second lines; Conductor is information communication apparatus that is formed at a position to be a point symmetry with respect to the first linear conductor in a plan view.

  The first plane is one surface of the printed circuit board, the second plane is the other surface of the printed circuit board, and the first linear conductor and the second linear conductor are: It may be a conductor formed inside a through hole formed in the printed board.

  The printed circuit board has a relative dielectric constant of 4.0 to 5.0, and a thickness of 6λ / 1000 to 45λ / 1000, where λ is a wavelength of a frequency to be used. The distance from the connection point of one linear conductor to the connection point of the conductive pattern and the second linear conductor is 75λ / 1000 to 225λ / 1000, and the conductive pattern is a length of one side. May be formed in a square shape of 225λ / 1000 to 450λ / 1000.

  The ground pattern may be formed so as to surround the power supply pattern, and the conductive pattern may be formed at a position facing the power supply pattern and the ground pattern.

  According to the present invention, even when it is thin, an electromagnetic coupler capable of increasing the coupling strength, widening the coupling range, and widening the frequency band to be used, and information communication equipped with the electromagnetic coupler Equipment can be provided.

  In addition, according to the present invention, it is possible to provide an electromagnetic coupler in which the information transfer characteristic hardly depends on the dielectric constant between the electromagnetic couplers and an information communication device equipped with the same while maintaining the information transfer characteristic equivalent to that of the conventional one.

  Furthermore, according to the present invention, an electromagnetic coupler capable of easily performing matching adjustment with a power feeding system and adjustment of a frequency band while maintaining information transmission characteristics equivalent to those of a conventional one, and an information communication device equipped with the electromagnetic coupler Can provide.

It is a figure which shows the electromagnetic coupler which concerns on one embodiment of this invention, (a) is the top view which looked at the electromagnetic coupler from the surface side, (b) is the back surface of the electromagnetic coupler from the surface side It is the top view seen through. (A), (b) is a figure which shows an example of the dimension of the electromagnetic coupler of FIG. It is a graph which shows the experimental result about the relationship between the frequency of the electromagnetic coupler of FIG. 2, and the absolute value of a reflection coefficient. It is a graph which shows the experimental result of ratio of the input electric power and output electric power to an electromagnetic coupler or a monopole antenna with respect to the distance between the electromagnetic coupler and monopole antenna of FIG. It is a top view of the monopole antenna used for the experiment of FIG. It is a figure which shows the experimental method of the experiment of FIG. It is a figure which shows the modification of the electromagnetic coupler of FIG. 1, (a) is the top view which looked at the electromagnetic coupler from the surface side, (b) sees through the back surface of the electromagnetic coupler from the surface side. FIG.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  1A and 1B are diagrams showing an electromagnetic coupler according to the present embodiment. FIG. 1A is a plan view of the electromagnetic coupler as viewed from the front side. FIG. It is the top view seen through from.

  As shown in FIGS. 1A and 1B, an electromagnetic coupler 10 is formed on a conductive pattern 11 formed on a first plane and a second plane parallel to the first plane, 12, a power supply pattern 13 connected to 12, a ground pattern 14 that is formed on the second plane so as to be separated from the power supply pattern 13, and is connected to the conductive pattern 11 and the power supply pattern 13. 15 and a plurality of second linear conductors 16 that connect the conductive pattern 11 and the ground pattern 14.

  In the present embodiment, a two-layer printed circuit board 17 capable of forming wiring patterns on both sides is used, and a conductive pattern 11 is formed on one surface (first layer, hereinafter referred to as surface) S of the printed circuit board 17. The power feeding pattern 13 and the ground pattern 14 are formed on the other surface 17 (second layer, hereinafter referred to as back surface) R of 17. That is, the first plane described above is the front surface S of the printed circuit board 17, and the second plane described above is the back surface R of the printed circuit board 17. Here, a case where a square FR4 (Frame Recipient Type 4) glass epoxy printed board is used as the printed board 17 will be described.

  The power supply pattern 13 is formed at the center of the back surface R of the printed circuit board 17 and is formed in a circular shape in plan view. The ground pattern 14 is provided so as to surround the periphery of the power supply pattern 13 with a gap 18 formed around the power supply pattern 13 interposed therebetween, and covers the entire back surface R of the printed circuit board 17 around the power supply pattern 13. It is formed and formed in a square shape in plan view.

  The conductive pattern 11 is formed on the surface S of the printed circuit board 17 so as to face the power supply pattern 13 and the ground pattern 14. The conductive pattern 11 is formed in a square shape that is slightly smaller than the surface S of the printed circuit board 17. That is, the conductive pattern 11 is formed in a square shape that is slightly smaller than the ground pattern 14. However, the conductive pattern 11 may be formed in a square shape having the same size as the ground pattern 14.

  The first linear conductor 15 and the plurality of second linear conductors 16 are formed perpendicular to the front surface (first plane) S and the back surface (second plane) R of the printed circuit board 17. These linear conductors 15 and 16 are conductors formed inside through holes (not shown) formed in the printed circuit board 17. The conductor may be filled in the through hole, or may be thinly provided on the inner surface of the through hole.

  One end of the first linear conductor 15 is connected to the center of the power supply pattern 13 (center in plan view), and the other end is connected to the center of the square conductive pattern 11 (center in plan view). As a result, the power supply pattern 13 and the conductive pattern 11 are electrically connected via the first linear conductor 15. The conductive pattern 11 has a shape that is point-symmetric with respect to the connection point A with the first linear conductor 15.

  The plurality of second linear conductors 16 have one end connected to the ground pattern 14 and the other end connected to the conductive pattern 11. Thereby, the ground pattern 14 and the conductive pattern 11 are electrically connected via the plurality of second linear conductors 16.

  The plurality of second linear conductors 16 are formed at positions that are point-symmetric with respect to the first linear conductor 15 in plan view. In the present embodiment, a total of eight second linear conductors 16 are formed, two in the vicinity of the four sides of the square conductive pattern 11. These eight second linear conductors 16 are formed at positions that are point-symmetric with respect to the first linear conductor 15 in a plan view, and that are vertically and laterally symmetric. The eight second linear conductors 16 are distances from the connection point A between the conductive pattern 11 and the first linear conductor 15 to the connection point between the conductive pattern 11 and the second linear conductor 16. L1 is formed so as to be all equal.

  When a printed circuit board 17 having a relative dielectric constant of 4.0 to 5.0 is used, the thickness T of the printed circuit board 17 is 6λ / 1000 to 45λ / 1000, where λ is the wavelength of the frequency used. The The distance L1 from the connection point A between the conductive pattern 11 and the first linear conductor 15 to the connection point between the conductive pattern 11 and the second linear conductor 16 is 75λ / 1000 to 225λ / 1000. The conductive pattern 11 is formed in a square shape having a side length L3 of 225λ / 1000 to 450λ / 1000. Further, the shortest distance between the two second linear conductors 16 provided in the vicinity of one side of the conductive pattern 11 and the two second linear conductors 16 provided in the vicinity of the adjacent side. The distance L2 is 75λ / 1000 to 225λ / 1000, and the length L4 of one side of the ground pattern 14 is equal to or longer than the length L3 of one side of the conductive pattern 11. Each of these dimensions is necessary to realize an input impedance that takes an appropriate matching condition of the electromagnetic coupler 10.

  More specifically, for example, when the frequency used is 4.5 GHz, the relative dielectric constant of the printed circuit board 17 is 4.4, the thickness T is 1.6 mm, and the dimensions of the electromagnetic coupler 10 are as shown in FIG. It should be set as follows. Although the thickness T of the printed circuit board 17 is 1.6 mm here, the thickness T of the printed circuit board 17 can be set to 1 mm or less by adjusting each dimension.

  Power supply from the power supply system 12 to the electromagnetic coupler 10 can be performed by, for example, a coaxial cable. The central conductor of the coaxial cable is connected to the power supply pattern 13, and the outer conductor of the coaxial cable is connected to the ground pattern 14.

  By supplying power from the power feeding system 12 to the electromagnetic coupler 10, a current flows through the first linear conductor 15, the conductive pattern 11, and the plurality of second linear conductors 16, and the plurality of second linear conductors 16 are connected to the electromagnetic coupler 10. From the flowing current, a longitudinal wave component of the electric field is radiated in a direction parallel to the second linear conductor 16 (a direction perpendicular to the conductive pattern 11). The magnitude of the longitudinal wave component has a positive correlation with the matching condition between the electromagnetic coupler 10 and the power feeding system 12.

  The operation of the electromagnetic coupler 10 will be described.

  The electric field generated from the minute dipole (Il) includes a longitudinal wave Er and a transverse wave Eθ. The longitudinal wave Er is expressed by the equation (1) shown in [Equation 1], and the transverse wave Eθ is expressed by the equation (2) shown in [Equation 2] (Non-Patent Document 1).

  Here, Il is a minute dipole passing through the origin 0 on the Z axis, Er is a longitudinal wave at the observation point P, Eθ is a transverse wave at the observation point P, r is a distance from the minute dipole to the observation point P, k0 represents the wave number, j represents the imaginary unit, w represents the angular frequency, ε0 represents the dielectric constant of vacuum, and θ represents the angle formed by the Z axis (microdipole) and the observation point P.

  In the equations (1) and (2), the component inversely proportional to the distance r is a radiation electric field, the component inversely proportional to the square of the distance r is an induced electric field, and the component inversely proportional to the cube of the distance r is an electrostatic field. The transverse wave Eθ is composed of a radiation field, an induction field, and an electrostatic field, whereas the longitudinal wave Er is composed only of an induction field and an electrostatic field.

  Since the radiated electric field is inversely proportional to the distance r, the radiated electric field reaches without being attenuated farther than an induced electric field or an electrostatic field that is inversely proportional to the square or the third power of the distance r. There is a risk of becoming. Therefore, in the electromagnetic coupler, information is transmitted using the longitudinal wave Er that does not include the component of the radiation electric field while suppressing the transverse wave Eθ.

  In the electromagnetic coupler 10 of the present invention, the second linear conductor 16 is formed at a position that is point-symmetric with respect to the first linear conductor 16 in plan view. A large current flows in the opposite direction, and the transverse waves generated in the conductive pattern 11 cancel each other. In the electromagnetic coupler 10, the length of the second linear conductor 16 (that is, the thickness T of the printed circuit board 17) can be shortened, for example, 1 mm or less. A transverse wave that is an electric field generated in the vertical direction can be reduced. Therefore, it is possible to suppress a transverse wave including a radiation electric field that becomes a disturbance wave to another system.

  When the length of the second linear conductor 16 is shortened, the longitudinal wave generated in the second linear conductor 16 is also reduced. However, in the electromagnetic coupler 10, a plurality of second linear conductors 16 (here, 8), and by increasing the number of second linear conductors 16 that are the sources of longitudinal waves, the magnitude of longitudinal waves generated in the entire electromagnetic coupler 10 is maintained, and the coupling strength is increased. It can be kept high.

  Further, when the distance between the conductive pattern 11 and the ground pattern 14 becomes short, the impedance characteristic becomes steep and the usable frequency band becomes narrow. However, in the electromagnetic coupler 10 of the present invention, the conductive pattern 11 and the ground pattern 14 are grounded. Since the pattern 14 is electrically connected to the second linear conductor 16, the second linear conductor 16 serves as a so-called short stub, makes the impedance characteristic gentle, and the conductive pattern 11 and the ground pattern. Even if the distance to 14 is reduced, the usable frequency band can be maintained widely.

  For example, the electromagnetic coupler of patent document 1 does not have the electrode grounded, and can be said to be an open stub electromagnetic coupler. The input admittance Y in the open stub can be expressed by Expression (3) shown in [Formula 3] from Patent Document 2. In addition, when Equation (3) is 0 <αθ << 1, and θ = (2m−1) π + δθ, | δθ | << 1, Equation (4) shown in [Expression 4] Can be approximated.

  Here, Y0 is the characteristic admittance, α is the loss constant, β is the wave number, l is the electrical length, and m is a positive integer. Since the electromagnetic coupler is desired to be small, m = 1 is used.

  From equation (4), the input admittance Y in the open stub is such that the real component takes an extreme value and the imaginary component becomes 0 in the vicinity of θ = (2m−1) π.

  On the other hand, the electromagnetic coupler 10 of the present invention has the conductive pattern 11 grounded, and can be said to be a short stub electromagnetic coupler. The input admittance Y in the short stub can be expressed by Expression (5) shown in [Formula 5] from Patent Document 2. Further, when the formula (5) is 0 <αθ << 1, and θ = 2mπ + δθ, | δθ | << 1, approximation can be performed as the formula (6) shown in [Equation 6]. is there.

  From Equation (6), the input admittance Y in the short stub is such that the real component takes an extreme value and the imaginary component becomes 0 in the vicinity of θ = 2mπ.

  Comparing equation (4) and equation (6), the slope of the real component and imaginary component of input admittance Y with respect to θ is smaller in equation (6) representing input admittance Y in the short stub. Therefore, as compared with the conventional open stub electromagnetic coupler, the electromagnetic coupler 10 of the present invention, which is a short stub electromagnetic coupler, has a gentle impedance characteristic and a close distance between the conductive pattern 11 and the ground pattern 14. Even so, the usable frequency band can be maintained widely.

  FIG. 3 shows the experimental results of investigating the relationship between the frequency of the electromagnetic coupler 10 of the present invention and the absolute value of the reflection coefficient. In this experiment, the electromagnetic coupler 10 having the shape shown in FIG. 2 was used. The electromagnetic coupler 10 is formed by using a FR4 double-sided (two-layer) substrate having a thickness of 1.6 mm. The dimensions of the electromagnetic coupler 10 are as shown in FIG. The absolute value of the reflection coefficient was measured using a network analyzer.

  According to the experimental results of FIG. 3, the absolute value of the reflection coefficient is 0.7 or less at a frequency of 4.08 GHz to 4.75 GHz. Therefore, it can be seen that the electromagnetic coupler 10 realizes a broadband frequency characteristic.

  FIG. 4 also shows the input to the electromagnetic coupler 10 or monopole antenna for the distance between the two electromagnetic couplers 10 and the distance between the two monopole antennas for the electromagnetic coupler 10 and the monopole antenna of the present invention. It is the experimental result which investigated the relationship between electric power and the ratio of output electric power. In this experiment, a monopole antenna 51 shown in FIG. 5 was used. The monopole antenna 51 includes a printed circuit board 52 and two rectangular conductors 53a and 53b formed on the surface of the printed circuit board 52. The two rectangular conductors 53a and 53b are formed apart from each other, the rectangular conductor 53a operates as a radiation conductor, and the rectangular conductor 53b operates as a ground. Power is supplied between the rectangular conductors 53a and 53b. The monopole antenna 51 is formed using a FR4 single-sided substrate having a thickness of 2.4 mm, and L′ 1 = 22.0 mm, L′ 2 = 10.0 mm, L′ 3 = 1.0 mm, L′ 4 = 20. 0.0 mm, L′ 5 = 9.5 mm, and L′ 6 = 1.0 mm. The monopole antenna 51 is a commonly used antenna and is applied to wireless communication using a transverse wave.

  The experimental system will be described with reference to FIG. In the experiment, the two measured objects 61a and 61b, that is, the two electromagnetic couplers 10 or the two monopole antennas 51 are arranged to face each other in parallel, and a perpendicular passing through the center of one measured object 61a is It arrange | positions so that it may pass through the center of the other to-be-measured object 61b. The measured objects 61a and 61b are connected to two terminals of one network analyzer 63 via coaxial cables 62a and 62b. Ratio of power input from the other terminal to power output from one terminal of the network analyzer 63 (absolute value of S21), that is, ratio of input power and output power to the electromagnetic coupler 10 or the monopole antenna 51 To evaluate.

  FIG. 4 shows experimental results regarding the relationship between the absolute value of S21 and the distance between the two electromagnetic couplers 10 of FIG. 2 and the two monopole antennas 51 of FIG. In the experiment, a signal having a frequency of 4.5 GHz is used, and the horizontal axis in FIG. 4 is the ratio of the distance between the measured objects 61a and 61b to the wavelength of the used frequency.

  As can be seen from FIG. 4, in the electromagnetic coupler 10 of the present invention, since the wireless communication is performed using the longitudinal wave whose attenuation with respect to the distance is larger than the transverse wave, the monopole antenna 51 that performs the wireless communication using the transverse wave is more effective against the distance. The slope of the absolute value of S21 is large. For example, when the ratio of the distance between the measured objects 61a and 61b with respect to the wavelength is around 0.7, the absolute value of S21 of the electromagnetic coupler 10 is about -37 dB while the monopole antenna 51 is about -18 dB. It is. On the other hand, as the distance between the measured objects 61a and 61b with respect to the wavelength decreases, the difference between the absolute values of S21 of the electromagnetic coupler 10 and the monopole antenna 51 decreases. Therefore, it can be seen that the electromagnetic coupler 10 has a relatively weak wireless communication strength at a distance, and is suitable for short-range wireless communication.

  As described above, in the electromagnetic coupler 10 according to the present embodiment, the conductive pattern 11 formed on the first plane and the second plane parallel to the first plane are formed on the power feeding system 12. The power supply pattern 13 to be connected is formed on the second plane so as to be separated from the power supply pattern 13, and the ground pattern 14 to be grounded is formed to be perpendicular to the first plane and the second plane. 11 and a first linear conductor 15 that connects the power supply pattern 13, and a plurality of second conductors that are formed perpendicular to the first plane and the second plane and connect the conductive pattern 11 and the ground pattern 14. Linear conductor 16, and the conductive pattern 11 is formed in a point-symmetric shape with respect to the connection point A with the first linear conductor 15, and the plurality of second linear conductors 16 are It is formed at a position that is point-symmetric with respect to the first linear conductor 15 in plan view. .

  According to the electromagnetic coupler 10, since the plurality of second linear conductors 16 that are longitudinal wave generation sources are formed, the thickness of the longitudinal waves generated by the respective second linear conductors 16 is small because the thickness is thin. Even in this case, it is possible to maintain the magnitude of the longitudinal wave generated in the entire electromagnetic coupler 10, and it is possible to maintain the coupling strength high.

  According to the electromagnetic coupler 10, since the plurality of second linear conductors 16 serve as short stubs, the impedance characteristic is moderated and the frequency band to be used is widened even when the thickness is reduced. Is possible.

  In addition, since the plurality of second linear conductors 16 serve as short stubs, the conductive pattern 11 is made larger (here, in order to achieve the same matching condition as compared with the case of the open stub). Then, the length of one side is 225λ / 1000 to 450λ / 1000), and the distance between the first linear conductor 15 and the second linear conductor 16 is increased (here, 75λ / 1000 to 225λ / 1000). Need to do. That is, in the electromagnetic coupler 10, the distance between the first linear conductor 15 and the second linear conductor 16 can be increased, and a plurality of second linear conductors 16 are connected to the first linear conductor 16. Since the second linear conductors 16 that are longitudinal wave generation sources are widely distributed because they are formed in a point-symmetrical position with respect to the conductor 15, it is possible to widen the coupling range. Therefore, even when the positions of the electromagnetic coupler 10 on the transmission side and the electromagnetic coupler 10 on the reception side are slightly shifted, information can be transmitted, which contributes to improvement in convenience.

  Further, in the electromagnetic coupler 10, the plurality of second linear conductors 16 are formed at positions that are point-symmetric with respect to the first linear conductor 15, so that the transverse waves generated by the current flowing through the conductive pattern 11 are mutually connected. The generation of transverse waves including the radiated electric field can be suppressed by canceling each other. Furthermore, since the electromagnetic coupler 10 can be thinned, the transverse wave generated in the second linear conductor 16 can also be suppressed. As can be seen from a comparison of the above formulas (1) and (2), since the transverse wave is half the longitudinal wave, the electromagnetic coupler 10 is made thinner (the second linear conductor 16 is reduced). If it is short), the transverse wave becomes very small. Therefore, the electromagnetic coupler 10 suitable for short-range wireless communication without interfering with other wireless communication systems can be realized.

  Furthermore, since the electromagnetic coupler 10 does not use a band-pass filter structure as in the prior art, it is possible to reduce deterioration in information transmission characteristics based on the change in the dielectric constant between the electromagnetic couplers described above. That is, according to the present invention, it is possible to realize the electromagnetic coupler 10 whose information transmission characteristic hardly depends on a change in dielectric constant with the other electromagnetic coupler that transmits information. As a result, even when an electromagnetic coupler is built in a device covered with a cover containing a dielectric, it is possible to reduce deterioration of information transmission characteristics, and to more types of information communication devices. Adaptation is easy.

  Note that in the conventional electromagnetic coupler, an electrode, a series inductor, a parallel inductor, and a capacitor are necessary to realize a bandpass filter, and the electrode is arranged in a layer independent of the series inductor and the ground pattern. It is a structure. As one of methods for realizing this, there is a method in which series and parallel inductors are formed on the surface of a two-layer printed circuit board, a ground pattern is formed on the back surface, and another electrode is connected thereto. Further, there is a method in which electrodes, series and parallel inductors, and ground patterns are formed in each layer using a three-layer printed circuit board, and the electrodes and the inductor are connected by a linear conductor. However, such a method complicates the structure of the electromagnetic coupler and increases the cost. On the other hand, in the present invention, the electromagnetic coupler 10 can be realized by using the two-layer printed circuit board 17, and for example, a printed circuit board with FR 4 interposed can be used. Therefore, according to the present invention, the electromagnetic coupler 10 having a simple structure and low cost can be realized.

  In addition, according to the present invention, the electromagnetic coupler 10 can be designed without considering the realization of the bandpass filter. Therefore, the matching adjustment with the power feeding system 12 can be performed while maintaining the information transmission characteristics equivalent to the conventional one. Can be easily performed. Therefore, when the electromagnetic coupler 10 is mounted on a device, it is necessary to adjust the frequency characteristics of the electromagnetic coupler 10 depending on the space in which the electromagnetic coupler 10 is arranged and the surrounding environment. Since it can be performed easily, the time required for this adjustment can be reduced, and the optimum electromagnetic coupler 10 can be quickly provided.

  The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, a case has been described where two second linear conductors 16 are formed in the vicinity of the four sides of the square conductive pattern 11, that is, a total of eight second linear conductors 16. The number and arrangement of 16 are not limited to this, and, for example, as in the electromagnetic coupler 71 shown in FIGS. If possible, a total of four second linear conductors 16 may be formed one by one near the four sides of the square conductive pattern 11. According to the electromagnetic coupler 71, four through-holes can be reduced as compared with the electromagnetic coupler 10 of FIG. 1, so that it is possible to realize an electromagnetic coupler with lower cost.

  In the above embodiment, the case where the conductive pattern 11 is formed in a square shape has been described. However, the conductive pattern 11 may have a shape that is point-symmetric with respect to the connection point A with the first linear conductor 15. For example, a circular shape or a polygonal shape may be used.

  Furthermore, in the above-described embodiment, the case where the conductor pattern 11 is formed on the front surface S of the two-layer printed circuit board 17 and the power supply pattern 13 and the ground pattern 14 are formed on the rear surface R has been described. It is also possible to use three or more printed circuit boards and use any two layers of the printed circuit boards. In the above embodiment, the electromagnetic coupler 10 using the two-layer printed circuit board 17 is shown. However, the electromagnetic coupler is formed by using a conductive plate made of a conductor such as copper or iron without using the printed circuit board 17. It is also possible to form.

DESCRIPTION OF SYMBOLS 10 Electromagnetic coupler 11 Conductive pattern 12 Feeding system 13 Feeding pattern 14 Ground pattern 15 1st linear conductor 16 2nd linear conductor 17 Printed circuit board

Claims (8)

A conductive pattern formed on the first plane;
A feeding pattern formed on a second plane parallel to the first plane and connected to a feeding system;
A ground pattern formed on the second plane and spaced apart from the power supply pattern, and grounded; and formed perpendicular to the first plane and the second plane; the conductive pattern and the power supply pattern; A first linear conductor connecting
A plurality of second linear conductors formed perpendicular to the first plane and the second plane and connecting the conductive pattern and the ground pattern;
With
The conductive pattern is formed in a shape that is point-symmetric with respect to a connection point with the first linear conductor,
The plurality of second linear conductors are formed at positions that are point-symmetric with respect to the first linear conductor in plan view. The first plane is one side of a printed circuit board;
The second plane is the other side of the printed circuit board;
The electromagnetic coupler according to claim 1, wherein the first linear conductor and the second linear conductor are conductors formed inside through holes formed in the printed circuit board. The printed circuit board has a relative dielectric constant of 4.0 to 5.0, and a thickness of 6λ / 1000 to 45λ / 1000, where λ is a wavelength of a frequency to be used,
The distance from the connection point between the conductive pattern and the first linear conductor to the connection point between the conductive pattern and the second linear conductor is 75λ / 1000 to 225λ / 1000,
The electromagnetic coupler according to claim 2, wherein the conductive pattern is formed in a square shape having a side length of 225λ / 1000 to 450λ / 1000. The ground pattern is formed so as to surround the power supply pattern,
The electromagnetic coupler according to claim 1, wherein the conductive pattern is formed at a position facing the power feeding pattern and the ground pattern. An information communication device equipped with an electromagnetic coupler and transmitting information using at least one of an electrostatic field and an induced electric field,
The electromagnetic coupler is
A conductive pattern formed on the first plane;
A feeding pattern formed on a second plane parallel to the first plane and connected to a feeding system;
A ground pattern formed on the second plane and spaced apart from the power supply pattern, and grounded; and formed perpendicular to the first plane and the second plane; the conductive pattern and the power supply pattern; A first linear conductor connecting
A plurality of second linear conductors formed perpendicular to the first plane and the second plane and connecting the conductive pattern and the ground pattern;
With
The conductive pattern is formed in a shape that is point-symmetric with respect to a connection point with the first linear conductor,
The plurality of second linear conductors are formed at positions that are point-symmetric with respect to the first linear conductor in plan view. The first plane is one side of a printed circuit board;
The second plane is the other side of the printed circuit board;
The information communication device according to claim 5, wherein the first linear conductor and the second linear conductor are conductors formed inside through holes formed in the printed circuit board. The printed circuit board has a relative dielectric constant of 4.0 to 5.0, and a thickness of 6λ / 1000 to 45λ / 1000, where λ is a wavelength of a frequency to be used,
The distance from the connection point between the conductive pattern and the first linear conductor to the connection point between the conductive pattern and the second linear conductor is 75λ / 1000 to 225λ / 1000,
The information communication device according to claim 6, wherein the conductive pattern is formed in a square shape having a side length of 225λ / 1000 to 450λ / 1000. The ground pattern is formed so as to surround the power supply pattern,
The information communication device according to claim 5, wherein the conductive pattern is formed at a position facing the power feeding pattern and the ground pattern.

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